Kiri Katou is a first-year student at Kaimei High School who is descended from real ninja. He likes doing things his own way and hates taking orders from others. He becomes the General Affairs Manager for the Student Council after Michiru graduates.

In middle school, his friend Kihara was harassed on a regular basis. Unable to effect the situation to any large degree himself, Katō asked a teacher to intervene. Unfortunately, the teacher turned out to also be tormenting Kihara and made the situation even worse, leading the latter to be shunned by the entire class. As a result, Katō lost faith in the idea of relying on others.

Katō likes doing things on his own or with his own way and hates taking orders from others. He has a tendency to speak bluntly and act spontaneously. After he acknowledges Tsubaki, he becomes fiercely protective of the latter and less adamant about working alone, now choosing to follow whatever Tsubaki wants him to do, which includes working together with the rest of the Student Council.